1. Field of the Invention
The present invention relates to the field of machining tools such as boring bars and more particularly to improved boring bars with adjustable cartridges. The boring bar includes a slotted area at one of its ends with an arcuate bottom face on which a correspondingly shaped surface of an anvil is seated. The boring bar also includes means for causing the anvil to slide upon a radiused surface of the boring bar and to rotate the anvil and cutting insert affixed thereto against a tension spring relative to the boring bar a key pin and key seat are provided to retain the anvil at the end of the bar. Set screws are eliminated as the cartridge is held in place by tension generated against the coil spring and the key pin.
2. Description of the Related Art
Pataky, U.S. Pat. No. 3,885,282 describes a machining tool including a holder and insert to which a cutting tool can be attached. The insert is rotatably mounted in a recess in the holder and fixed in a desired position relative to the holder by a locking screw. Rotatable adjustment o the insert allows for the altering of the tip working angle.
Jester et al., U.S. Pat. No. 4,631,994 describe a linearly and angularly adjustable holder for a cutting tool. Such tool permits pivotal adjustment by means of an adjustment screw having a threaded portion seated in a basic element and a head which engages a recess in a rotatably mounted receptacle element which holds a cutting tool insert. Rotation of the adjustment screw causes rotation of the receptacle element.
However, the structures described in the above mentioned patents are not directed to alleviating the problem of "stacked" tolerances. In addition, high speed boring bars cannot meet the precision cutting parameters required today with traditional cartridges mounted to the periphery of the boring bar due to the chatter created. Although creating a recess large enough to seat the cartridge within the bar amy stabilize the bar, radial adjustment where the adjustment force is directed against the bar would still induce bowing of the bar in narrow diameter boring bars.
Reiterman, U.S. Pat. No. 4,927,301, which is incorporated by reference as if fully set forth herein, is directed to an improved boring bar which meets the shortcomings of bowing and stacked tolerances. The bar is equipped with an anvil shaped cartridge which fits into a radiused bottom shaped groove in the bar. The anvil is adjusted by means of loosening a set screw, adjusting the anvil by means of an arcuate headed screw which forced the anvil against a spring washer retained by another screw at the opposite end of the anvil, and then, when the desired position is reached, the set screw is again rotated to lock the assembly in place.
The present invention is an improvement over U.S. Pat. No. 4,927,301. The lock screw is eliminated, as are the spring washers. The method of operation is thereby simplified to a one step adjustment, thereby resulting in ease of operation, elimination of the set screws, and substantial labor savings.
Noggle et al, U.S. Pat. No. 5,154,551 relates to an improved adjustable boring bar having an adjustable cartridge including an anvil rotatably affixed to the boring bar. The cartridge is located at a point intermediate the ends of the bar. The anvil is secured in an axially oriented slat which includes an arcuate seating face. A leaf spring arrangement is used to urge the anvil against a single adjustment screw. Rotation of the anvil within the slot effects radial adjustment of the insert.
The present invention is designed to address boring bars wherein the adjustable anvil is carried at the end of the boring bar.
It is therefore an object of the present invention to provide an adjustable insert cartridge recessed at one end of the boring bar where the force required for radial adjustment of the inserts is insufficient to induce bowing a boring bar.
It is a further object to provide an adjustable cartridge which is properly balanced in high speed applications and which reduces the stroke necessary to clear the bar from a hole in a work piece. Also it is possible to adjust both size and lead angle or back taper.
Finally, it is a further object of this invention to provide an adjustable cartridge which is easily adjusted and which holds the cartridge in place without the need for lock screw.